Is san-T in vent run allowed?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Earl, Jul 28, 2014.

  1. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    For an island sink waste and vent I'm using the recommended approach that is posted in many locations (see attached). However this application is not an island but rather against a pony wall in an open floor plan. The pony wall flows into the main load bearing post. Since I can't drill through it I'm routing down and around.

    The plan shows Combo T-Wye's for the foot vent run into the vent return line. My application makes that somewhat difficult due to the height loss (the main line is ~30' from this drain). Due to geometry the foot vent is running perpendicular to the floor joists so that is already 5.5" below the floor. Just below the plywood floor, I'm using a 45 angle around a girder so the angle does help reduce the drop. (I thinking of adding another 22.5 angle to minimize further). To shorten it up can I use a san-T in place of the upper combo?

    Since it is a vent do I need to use a long turn when routing back up through the wall after the post?

    Attached Files:

    Last edited: Jul 28, 2014
  2. asktom

    asktom Member

    Messages:
    564
    Location:
    Victor, MT
    HJ has a way of using a san tee rather than a combination, you can look it up or, now that I have invoked his name, wait for him to answer here. You do need a long 90 (or combination with a CO plug on the back) when a vent goes from horizonal to vertical and is not 6" above the flood level (the countertop in this case).
  3. Terry

    Terry Administrator Staff Member

    Messages:
    15,041
    Location:
    Bothell, Washington
    All fittings below flood lever need to be installed as waste fittings with cleanouts. The cleanout isn't going to do you much good if you've installed a vent fitting, something I don't even stock.

    If you are worried about height, you can lay those fittings horizontal with wyes.
    The picture is just one way of doing that.
    The takeoff on the vertical for the foot vent could have been a santee in that position.
  4. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    Sorry, this part confused me. Where is the "takeoff" your are referring to? The first part of your post seems to say I must use a Combo T-Wye's for the "Foot vent" connection at the return vent loop but this also appears to be the "takeoff" to me. It is below the flood line. In my application the fitting is at 45 deg (or perhaps 67.5 deg).

    I do understand from Tom that I need a long 90 (or combo with cleanout) for the point in the figure labled "Long turn below fixture flood rim."

    I did a search for HJ posts but couldn't find the post you refer to. He has so many posts! As a side note, I'm always fascinated by the various posts here. It always reinforces my respect for what good plumbing really is. The site has made me much more knowledgeable and confident. In one particular case many years ago I found a “professionally” installed run from our laundry room remodel that was not correctly supported on 4’ centers. As a result, it did not slope properly and, in fact went to a very slight positive grade in one section! Of course this wasn’t detected for a year or so until I was under the house in the crawl space for another reason. It was a simple matter to replace and reconnect at the required ¼” per foot. In the early days of owning my home I would have never questioned what a professional plumber did.
  5. Reach4

    Reach4 Active Member

    Messages:
    2,302
    Location:
    IL
    pix2.png Your pix with some numbers added.
  6. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    Thanks! So it is fitting in question is #12.

    Some other specifics: I was planning on a combo with cleanout for #4. Since I can't place a cleanout at location #15 I was thinking of adding a cleanout/test fitting just above #12 after the 45 deg bend but below the floor (the crawlspace under the house will make this accessable). Per the code discussion with Tom on a different thread I was only going to use one san tee at the #6/#7 location. I have #14 as a long 90.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    1. A cleanout at #15 is the only way you would be able to clear the horizontal vent section.
    2. The #6 cleanout would be preferable to on at #4, but keep the #4 tee for the drain connection.
    3. You can turn #12 combo on it back and tie it into a street sanitary tee in pipe #5.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    There are many ways to configure the "foot" vent and it connections, but it depends on the actual situation as to which is best, i.e., which way the drain runs relative to the above floor piping, actual height restrictions, etc.
  9. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    Thanks HJ. I’m not sure I understood this part. Are you saying: delete #2, rotate #12 clockwise 90 deg, flip horizontally (so flow is to right), connect to an added san-T just above 4? That would make sense. But because I have to route around a girder below the wall, the added san-T can’t be vertical, it would have to be at 45 deg or 67.5 deg (same angle as the repositioned #12). Given that, is this still OK to do?

    Good point about the horizontal vent section - I was worried about the vertical vent #11 but, now that you mention it, the horizontal #13 is looks more important. Since I can’t put a cleanout at #15, perhaps a combo at #14 with a cleanout? Or I could add a test-T clean-out somwhere along #13 with a long 90 at #14. your thoughts?

    Keeping #6 is a great idea. Any issue with installing it as a street san-T into the san-T at #7? That will minimize the distance to #7. I like this even better as it allows access without having to go under the house! I’ll keep the combo at #4 as you suggest for maximum flexibility.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    A street san tee for the drain, into a "test tee" will give you a good cleanout. I am not sure what you are saying about the angle, such as where exactly is the beam and which way would the angles be. Because of that uncertainty, I am not sure how to tell you to make that connection.
  11. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    Sorry it wasn't clear. The construction is raised foundation with girders on post-piers supporting floor joists. The sink cabinetry is against a half height wall that transitions to a standard wall a few feet to the right. This wall is where the plumbing resides.

    The wall is parallel to and right above the main girder supporting the kitchen and adjacent living room floor. That is, directly below the bottom plate, after the perpendicular joists, there is a 4x6 girder running the length of the wall (and beyond). Viewed another way, after drilling the 2 ½” hold to feed the ABS piping though, if I look straight down, I see the top of the girder. Therefore, immediately after penetrating the plywood floor, I need at least a 45 deg fitting to route the drain away from the girder. Since the joists are 2x6’s there is just 5.5” to accomplish this.

    Imagine the above figure on a sheet of paper, if I folded the paper just below the “Floor” line at a 45 deg (or 67.5 deg) angle, that is what I'm trying to describe. Therefore, fixture #12 whether a combo or san-T won’t be vertical. The reason I thought this was important is that I read somewhere that san-T’s are for vertical orientations and not permitted in horizontal orientations. As you can see this application is somewhere in between.

    Because this is for venting purposes (other than rainwater from the roof routing), my instinct tells me that this application may be OK. But, I’ve learned from many posts on this forum that venting is not as straightforward as it may appear.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    Just install 45s right under the floor as the pipes come through the floor, then install everything in the picture as if they were in a vertical line even though they will be slanted 45 degrees from vertical. In other words, assume you did it JUST LIKE your picture, then cut all the vertical lines 1" below the floor, put 45s on them and then glued the bottom into the 45s, possibly cutting them off to compensate for the added length of the 45s.
  13. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    Yep, that's my plan. The question is whether I can use a san-T for fitting #12.
  14. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,184
    Location:
    Maine
    Yes you can
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,680
    Location:
    Cave Creek, Arizona
    If you do it the way I described, then NO.
  16. Earl

    Earl New Member

    Messages:
    17
    Location:
    El Segundo
    I don't plan on rotating #12 to tie it into a street sanitary tee in pipe #5. I'm going to basically follow the Reach4 plan with san-T at #12, clean-out somewhere along #13, and combo / clean-out at #4.

    thanks everyone.
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